September 2013
Beginner to intermediate
396 pages
8h 8m
English
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Chapter 11. Dates and Times
Dates and times are very common in data analysis—not least for time-series analysis. The bad news is that with different numbers of days in each month, leap years, leap seconds,[33] and time zones, they can be fairly awful to deal with programmatically. The good news is that R has a wide range of capabilities for dealing with times and dates. While these concepts are fairly fundamental to R programming, they’ve been left until now because some of the best ways of using them appear in add-on packages. As you begin reading this chapter, you may feel an awkward sensation that the code is grating on you. At this point, we’ll seek lubrication from the lubridate package, which makes your date-time code more readable.
Chapter Goals
After reading this chapter, you should:
-
Understand the built-in date classes
POSIXct,POSIXlt, andDate - Be able to convert a string into a date
- Know how to display dates in a variety of formats
- Be able to specify and manipulate time zones
-
Be able to use the
lubridatepackage
Date and Time Classes
There are three date and time classes that come with R: POSIXct, POSIXlt, and Date.
POSIX Dates and Times
POSIX dates and times are classic R: brilliantly thorough in their implementation, navigating all sorts of obscure technical issues, but with awful Unixy names that make everything seem more complicated than it really is.
The two standard date-time classes in R are POSIXct and POSIXlt. (I said the names were awful!) POSIX is a set of standards ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.